The sign of Chvostek is exaggerated response to physical stimulation of the facial nerve in patients with hypocalcemia. The maneuver and the sign were described in 1876 by the Czech physician František Chvostek.
The maneuver consists of percussion with a finger on the angle of the jaw, which is the site where the facial nerve is most superficial. In this way, the nerve is stimulated and if there is a movement of the facial muscles on the same side with this stimulation, the sign is positive.
By Patrick J. Lynch, medical illustrator - Patrick J. Lynch, medical illustrator, CC BY 2.5, Many functions of the body are regulated by calcium. Some of them are muscle movements, including the heart muscle and brain function. A calcium level in the blood below 8.8 g / dL is considered hypocalcemia.
Hypocalcemia can have consequences such as arrhythmias and seizures. Another common cause of this condition is accidental removal of the parathyroid glands in thyroidectomy surgery.
The parathyroids are glands that are responsible for releasing parathyroid hormone (PTH) that regulates the level of calcium in the body. When there is no parathyroid hormone, the general consumption of calcium is higher and generally decreases, leading the patient to a state of calcium deficiency or hypocalcemia.
What is the Chvostek sign?
Chvostek's sign is a physical manifestation that occurs due to hyperactivity of the facial nerve due to hypocalcemia, in response to an external stimulus. František Chvostek (1835-1884), a physician of Czech origin, was the one who described the maneuver and the sign in 1876.
Based on the evaluation of the history, symptoms and history of a patient, the doctor can orient his diagnosis towards the circulating calcium deficiency.
Patients who have undergone total thyroid removal surgery usually develop muscle cramps and hyperexcitability of the muscles with involuntary movements of the mouth within a day or two later. When this occurs, a hypocalcemia-oriented physical examination is carried out.
The maneuver begins with the patient seated and relaxed. The doctor proceeds to gently tap a finger at the angle of the jaw. The anatomical reason why this point is chosen is because it is there where the facial nerve makes its most superficial route and is easier to stimulate.
By MarcoMutMut - Own work, CC BY-SA 3.0, If the patient responds to the stimulus with an exaggerated movement of the lip corner and even the eye on the same side of the stimulation, the Chovstek sign will be positive, being an indicator to request the patient specific laboratory tests to measure the level of calcium in the blood.
An associated sign that may appear in this condition is Trosseau's sign, in which the patient has hyperflexion of the wrist joint when inflating a blood pressure cuff on the arm on the same side.
By Tmdswan - Own work, CC BY-SA 4.0, Trosseau's sign is more specific than Chovstek's sign when diagnosing hypocalcemia.
Parathyroid
The parathyroids are small glands that are located on the back of the thyroid gland in the central part of the neck. Usually there are four, but they can vary in number and be fewer or more.
By unknown for original imageMiguelferig for the Galician annotation - File: Illu thyroid parathyroid.jpg, Public Domain, The main function of these glands is to produce and release parathyroid hormone (PTH) into the blood. This hormone maintains the calcium balance in the body.
When the gland detects low levels of calcium in the blood, it begins the production and secretion of PTH. Likewise, when calcium levels in the blood increase, contrary mechanisms occur that stop the release of PTH.
Parathyroid hormone has a direct effect on the bones, kidneys and small intestine, since these are the sites where the absorption and resorption of calcium is regulated. Finally, its action on these sites has an impact on the level of calcium in the blood.
By Mikael Häggström - All used images are in public domain., Public Domain, Calcium is an essential element for the proper functioning of the muscles, the heart, the bones, the kidneys and the nervous system.
Within cells, in the mitochondria, there are calcium channels that regulate their function. When there is an imbalance in the calcium level, a cellular imbalance occurs that leads to organ dysfunction.
Hyperparathyroidism
Although pathologies of the parathyroid glands are not very frequent, hyperparathyroidism is a condition that can present in the surgical consultation.
Hyperparathyroidism is defined as overactivity of the parathyroid. It has several causes, but the most common is the presence of an adenoma. Parathyroid cancer is a very rare pathology but it must be taken into account.
By BruceBlaus. When using this image in external sources it can be cited as: Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.010. ISSN 2002-4436. - Own work, CC BY 3.0, Adenoma is a type of benign tumor that increases the size of the gland, making it more active. In other words, it leads it to produce and secrete a greater amount of PTH.
Patients with hyperparathyroidism have hypercalcemia, that is, a greater amount of circulating calcium in the blood. Typical symptoms of hypercalcemia are fatigue, depression, bone pain, excessive thirst, and in some cases, kidney stones.
Resolution of a parathyroid adenoma is surgical.
Hypoparathyroidism
Hypoparathyroidism is a condition in which the activity of the parathyroids is decreased. This means that there is less PTH circulating in the blood.
The most common cause of hypoparathyroidism is accidental excision of the parathyroid glands when surgery is performed in which the thyroid is completely removed, called a total thyroidectomy.
Other less common causes are autoimmune diseases in which the immune system itself destroys parathyroid cells.
Hypoparathyroidism can be temporary or permanent. In any case, calcium supplement therapy should be started as soon as possible since the biochemical imbalance produced by the decrease in calcium in the body can lead to many complications, including death.
Decreasing the level of calcium in the blood increases the excitability of the muscles and nerves. The patient with hypocalcemia may present symptoms such as involuntary movements of the muscles, commonly of the muscles of the face, called fasciculations.
When the doctor examines, he may notice an increase in the reflex response of the patient. These symptoms, together with an adequate history, guide the diagnosis of hypocalcemia.
References
- Omerovic, S; M, Das J. (2019). Chvostek Sign. Treasure Island (FL): StatPearls. Taken from: nlm.nih.gov
- Hujoel, IA (2016). The association between serum calcium levels and Chvostek sign: A population-based study. Clinical practice. Taken from: ncbi.nlm.nih.gov
- Lofrese, JJ; Basit, H; Lappin, SL. (2019). Physiology, Parathyroid. Treasure Island (FL): StatPearls. Taken from: nlm.nih.gov
- Khan, M; Sharma, S. (2019). Physiology, Parathyroid Hormone (PTH). Treasure Island (FL): StatPearls. Taken from: nlm.nih.gov
- Kamalanathan, S; Balachandran, K; Parthan, G; Hamide, A. (2012). Chvostek's sign: a video demonstration. BMJ case reports. Taken from: nlm.nih.gov
- Rehman, HU, & Wunder, S. (2011). Trousseau sign in hypocalcemia. CMAJ: Canadian Medical Association journal = journal de l'Association medicale canadienne. Taken from: nlm.nih.gov